This invention relates to a rubbing machine such as a portable sander of the type used by automotive body shops to prepare body parts for painting.
A popular sander of this type includes a power-rotated head which rotatably supports an eccentric spindle. A rubbing pad is clamped to the end of the spindle by a screw or the like and carries an abrasive disc. When the head is rotated, the spindle turns within the head and causes the pad and the abrasive disc to move with an orbital action.
In order to replace the rubbing pad, the screw is loosened and the pad is detached from the spindle. To enable loosening of the screw, the head carries a locking member which may be selectively moved between locked and unlocked positions. When the locking member is in its locked position, it engages the spindle and prevents the spindle from turning relative to the head so that the screw may be unthreaded from the spindle.
With prior sanders of this type, the locking member is in the form of a ring-like plate having upstanding dimples which are adapted to engage the head in order to confine the locking member radially relative to the head. The plate normally is offcenter relative to the head and tends to unbalance the sander. Moreover, the offcenter plate tends to hit obstructions and interfere with the sanding operation.
In some cases, the locking member of the prior sander may be improperly assembled in an upside down position and, in such an instance, the dimples are ineffective to radially retain the locking member. The unretained locking member may tear loose from the head and cause personal injury.